John Günther I of Schwarzburg-Sondershausen (also known as Hans Günther or Johann Günther; 20 December 1532 in Sondershausen – 28 October 1586 in Arnstadt) was the co-ruler of Schwarzburg from 1552 until 1571 and the sole ruler Schwarzburg-Sondershausen from 1571 until his death. He is regarded as the progenitor of the line Schwarzburg-Sondershausen.

Count John Günther I was the son of the Count Günther XL of Schwarzburg (1490–1552), nicknamed Günther the Rich or Günther with the large Jaws, and his wife Elisabeth (d. 14 May 1572), a daughter of Count Philip of Isenburg-Büdingen-Ronneburg.

After his father's death, John Günther I initially ruled Schwarzburg jointly with his three brothers. He chose the city of Sondershausen as his residence. In 1571, the brothers decided to divide the County. John Günther I's part was named Schwarzburg-Sondershausen, after its capital.

He fought in the Netherlands alongside his eldest brother Günther XLI and distinguished himself during the conquest of Saint-Quentin in 1583.

After his brothers Günther XLI of Schwarzburg-Arnstadt and William I of Schwarzburg-Frankenhausen had died withour male heirs, John Günther I inherited Schwarzburg-Arnstadt and his remaining brother Albert VII inherited Schwarzburg-Frankenhausen.